Mounting for spiral blading within frustoconical mixing chambers



' 1949 G. HlLKEMElER ETAL 2,490,215

MOUNTING FOR SPIRAL BLADING WITHIN .FRUSTO-CONICAL MIXING CHAMBERS Filed Jan. '10, 1946 mmm HAM H 1m H m w%m n mm m 8 3% w s\\ L V. B

Patented Dec. 6, 1 949 MOUNTING FOR SPIRAL BLADING WITHIN FRUSTOCONICALTMIXING CHAMBERS BeltCompany,Milwaukee,Wis.;"'a corporation of Wisconsin Application January 10, 194%, Serial ninth/;

i'cn'inii" (c1. zit-1'75 This 1 invention relates wimprov ments in concrete mixers such as are'mounted Ion motor i ks a is p r icularly 'eonceined"with the n'ej e mixing drum, Heretofore in the art of;manufacturing[jthe mixing drum for truck. iv

tion' it has'been found --neces sary to provide a mixing chamber with spiral blading which blad-j ing eiffectively moves the mixing aggregate from one endof'themixing chamber'to the other and} returnsit, all-the while mixingthe aggregate with itself and with water supplied to it,fas it courses frornend to end-of the-mixing-chamber. A concern toythoseinterestedin the art has been to make durable blading, .for the abrasive actionfof-the ,mixing aggregate n the blades forming the spiral; "shortens" their useful life. Also at the point where the spiral blade element is attached to the walls of the frusto-conical por-- tion of the mixing chamber, either the holding weld is quickly abraded, or, the jointure builds up with hardened aggregate. Another problem of no small importance has been the removal of the spiral mixing blades once they became worn to a point of uselessness.

Because of the difficulty of fastening a spiral element to the interior of a cone-like surface it was the practice, prior to the advent of the present invention, to weld the blading to the shell itself.

This practice necessitates costly manufacture, painful replacement, and inaccurate positioning of the spiral blading.

It is the object of this invention to provide improved blading which will substantially withstand the harsh, abrasive action and shocks of the coursing aggregate.

It is further the object of this invention to provide readily detachable blading for a mixing vessel having a frusto-conical portion which is mounted with its axis inclined to the horizontal.

Another object of this invention is to provide improved mounting means to the interior of a substantially pear shaped mixing drum for spiral blade elements.

Referring to'the drawings F 1 a i k sl etiqe ll. with parts broken away, showing he blading affixed to the mixing drum.

r 5 me n ri ebr ing instrumentalitie Fig, 3 isa' fsectiona 7 blade showing the bladeleme holdingfme'ans.

Fig.2. 7

In th difierent views 6r tn numerals refer to likef'p chargedirectionf"'By.

estuar ne? Figl i is a; section er-air ess; the fine i i:

als on...

the blades, a greater proportion is directedrea'r wardly and expelled through the opening.

The blades I2 are preferably made in segments which are fitted with their ends abutting so as to form continuous spirals. We have found that the most rearward of these segments, i. e., the segments [5, which terminate at the opening [3, may be best secured to the walls of the drum by welding or other means of permanent securement. The other portions or segments are detachably mounted as hereinafter described.

Permanent securement of the end segments l5 has been found desirable because a weld may be made along the entire jointure of the blade and the drum, thereby increasing the area of support, and because the end segments are pitched steeper to produce a chuting rather than a tumbling efiect, the welds are not as rapidly abraded as are the more remote segments which effect primarily tumbling of the mix.

Fillets [6, refer to Figs. 1 and 3, which are welded to each of the blade elements 12, extend over the jointure of the blading and the drum and forestall the building up of concrete in what would otherwise be a sharp pocket. The fillet I6 which is secured to the end spiral segment I is also welded to the drum, but the other fillets are secured only to the blading, thereby making the latter blading completely detachable.

The detachable blade portions are supported by clips H, which are constructed of metal and have a triangular base I8 with a transverse upstanding portion l9. The base conforms to the conical surface most readily. In fact, in some instances along the spiral blading, one leg of the triangular base coincides with the radial lines of the cone. This precludes a great amount of the bridging which would otherwise exist if a fiat surface were fitted against the conical wall of the drum. Also it readily facilitates the positioning of the clip in the fabrication of the complete mixing vessel.

Another advantage of this construction is that in reducing the bridging efiect, i. e., the open space between the base of the clip and the wall of the frusto-conical mixing chamber, less weld is needed to securely fasten the clip to the walls of the drum. Hence, the likelihood of burning through the drum in fabrication, using welding means, is lessened.

The flexibility of the improved clip is apparent from Fig. 3. Here the clip is shown with its triangular base [8 fastened to the conical wall II and with its upstanding portion [9 bent forward to position the blading so that the sections as shown in Fig. 3 are perpendicular to the axis of the drum. The filleted or curved edges of the clip are indicated at 20 in Fig. 4. These edges 20 may be as shown, or the entire top surface of the upstanding projection I9 may be curved so that the concrete may readily pass over it. This effectively eliminates any surface normal to the fiow of th mixing aggregate.

Fig. 3 is a cross section through the blading mounted to the mixing chamber. The blade elements [2 are attached to the clips IT by means ofbolts 2| or other holding means which extend through oblong apertures 22 in the holders and circular apertures 23 in the blades. It will be noted from this view that the fillet I6 is welded to the blade element l2, however, it merely abuts the wall of the mixing chamber II. This, of course, insures complete detachability and yet protects the jointure of the blade and walls of the mixing chamber and eliminates the building up of aggregate at this point.

To compensate for the spiral shape of the blade and to cause the upstanding portion [9 of the holder to lie fiat against the back of the blade, the portion l9 may be twisted as shown in Fig. 4, and the foot portion l8, as shown in Fig. 2, may also be twisted to permit both of the trailing edges thereof to be fitted up and welded to the wall of the drum. In different parts of the drum, the amount of the twist on these portions of the clip will vary, but in all cases a standard clip may be employed which can be easily shaped, by twisting, to fit any point of jointure between the blading and the drum.

Having thus described the invention, we claim:

In a drum for concrete mixers and the like arranged to rotate and having an axial opening at one end, a continuous spiral blade extending inwardly from the perimetrical walls of said drum and terminating adjacent said opening, said blade being made in segments with the portion adjacent the opening permanently secured to the drum and pitched at a steeper angle than the segments remote therefrom, whereby the material in the drum may be rapidly discharged through said openings and means detachably securing to the walls of the drum the segments of the blade remote from the opening.

LOUIS G. HILKEMEIER. ELMER G. HAHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,058,803 Smith Apr. 15, 1913 1,322,575 Jaeger Nov. 25, 1919 1,475,904 Vandenplas Nov. 27, 1923 1,781,823 Robbins Nov. 18, 1930 2,088,099 Venable July 27, 1937 2,167,243 Lichtenberg July 25, 1939 2,254,639 Andrae Sept. 2, 1941 FOREIGN PATENTS Number Country Date 490,474 Germany Dec. 30, 1926 

